Authentication techniques for authenticating users through a network have been used. Registration information, such as password information and biometric information, to be checked when authentication is performed is registered in advance in an authentication apparatus which performs the authentication, and the registration information is compared with input information at a time of the authentication. In accordance with a result of the comparison, a determination as to whether the authentication is successfully performed or fails is made. Such an authentication technique is employed, for example, in authentication functions of bank systems and authentication functions of e-commerce and electronic payment.
Furthermore, techniques of authenticating devices instead of persons have also been used. For example, apparatus authentication using a function of outputting values unique to apparatuses utilizing a so-called physical unclonable function (PUF) which is a physical characteristic in which generation of clones of the apparatus is difficult has been used.
Mainly, two types of authentication technique, that is, a technique referred to as one-to-one authentication and a technique referred to as one-to-N authentication (which is also referred to as ID-less authentication), have been used. In the one-to-one authentication, a user ID which identifies a corresponding user is received at a time of authentication, for example, so that certain registration information associated with the user ID is specified from among registration information registered in advance. Then, input information is compared with the certain registration information, and it is determined whether authentication has been successfully performed in accordance with a result of the comparison.
On the other hand, in the one-to-N authentication, user IDs are not received. Therefore, at a time of the authentication, input information is compared with a plurality of registration information. In the one-to-N authentication, input information is compared with all registration information and a determination as to whether authentication has been successfully performed is made in accordance with one of the registration information which is the most similar to the input information.
An authentication system which performs the one-to-N authentication is taken as an example (refer to Japanese Laid-open Patent Publication No. 2002-297549, for example). The authentication system executes personal authentication using a fingerprint. When fingerprint minutia data is to be registered, the authentication system assigns classification information to the fingerprint minutia data to be registered in accordance with similarity between reference data and the fingerprint minutia data. On the other hand, when the input fingerprint minutia data is to be compared, classification information of the input fingerprint minutia data is generated and fingerprint minutia data which is a target of the comparison is limited or priority levels are assigned to the fingerprint minutia data in accordance with the classification information of the input fingerprint minutia data.